Abstract
The Physical Self-Description Questionnaire (PSDQ; Marsh, Richards, Johnson, Roche, & Tremayne, 1994) is a self-report instrument designed for the measurement of various aspects of the physical self that has gained widespread recognition and initiated a significant amount of research. The PSDQ is based on the multidimensional and hierarchical self-esteem model of Shavelson, Hubner, and Stanton (1976). The current study employs Mixture Distribution Rasch models to compare the psychometric properties of two rating scale variants (original rating scale with 6 response categories, N = 806 youth; and a variant with 4 response categories, N = 905 youth) for the Physical Self-Description Questionnaire (PSDQ; Marsh, Richards, Johnson, Roche, & Tremayne, 1994). In most cases, 2-class solutions fit the data best, suggesting the presence of response sets. Logistic regression analyses help identify the characteristics of respondents in either of the 2 latent classes. In particular, individuals with lower educational levels appear to have problems with using as many as 6 response categories correctly. The results suggest that the administration of the PSDQ using a rating scale with 6 response categories can be problematic because the test scores' psychometric qualities may be substantially different across subgroups. Test developers should consider issues such as the one covered in the current research with the necessary cautiousness, and should carefully consider what the response format.
